I admit that I am new to ponding... but I DO have extensive knowledge on goldfish, freshwater, and saltwater aquariums.
You can NEVER have too much filtration. BUT... you can have too much cleaning of filtration. By this, I refer to the fact that beneficial bacteria grows inside your filter media and is a good thing... a VERY good thing. I have met people that literally scrub out their filter systems and change the filter media too often. This starts you back at ground zero to build up the good flora and fauna again.
Another myth is that all algae is bad. It is unsightly... but not necessarily bad. It can be a good sign in a new system that ballance is finally being acheived. You just do not want it to get out of hand. And it also depends on the type.